Ignore mapdir_with_leading_slash on Windows for now

These tests are failing because we call `take(N)` on chars of a string
read from a file. It seems that on Windows, the programs get line
endings with `\r\n`, this is a problem for the way our tests assert
correct output.

We'll need to find a general solution to this problem later.

tests/ignores.txt

@@ -61,12 +61,14 @@ wasitests::snapshot1::file_metadata on windows
 wasitests::snapshot1::fseek on windows
 wasitests::snapshot1::path_link on windows
 wasitests::snapshot1::path_symlink on windows
+wasitests::snapshot1::mapdir_with_leading_slash on windows
 wasitests::unstable::fd_pread on windows
 wasitests::unstable::fd_read on windows
 wasitests::unstable::file_metadata on windows
 wasitests::unstable::fseek on windows
 wasitests::unstable::path_link on windows
 wasitests::unstable::path_symlink on windows
+wasitests::unstable::mapdir_with_leading_slash on windows
 
 # This test is meant to only run on Unix
 wasitests::unstable::unix_open_special_files on windows